Update Unity.gitignore
Update Unity.gitignore

Ignore the build directory in case a Unity build is initiated in the project.
chhsieh/gitTest_1,szymanskirafal/gitignore,szymanskirafal/gitignore,bruennijs/ise.cppworkshop,chhsieh/helloworld,bruennijs/ise.cppworkshop,szymanskirafal/gitignore,bruennijs/ise.cppworkshop